Flexible substrates and method of manufacturing the same

ABSTRACT

A flexible substrate includes a flexible mother substrate and a planarization layer on the flexible mother substrate. Here, the flexible mother substrate includes a transparent textile and a resin layer. The transparent textile includes a plurality of first transparent fibers and a plurality of second transparent fibers crossing the plurality of first transparent fibers, and the resin layer coats the transparent textile to fill a space between the first and second transparent fibers. The planarization layer includes an organic material having a curable contraction rate of no greater than about 20%.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Korean Patent Application No.10-2011-0081359 filed on Aug. 16, 2011, the disclosure of which ishereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to flexible substrates and methods ofmanufacturing the same.

2. Description of the Related Art

Display devices display desired data through display panels. The datadisplayed by the display panel may be in various forms such as, forexample, words, stabilized images, or moving pictures. The displaydevices may be used in various electronic devices, and variouscharacters of the display devices may be required according to the formsof the electronic devices which are applied in connection with thedisplay devices.

To satisfy the various demands, display devices with flexibility may berequired. In other words, it may be required that the display devicesare capable of being folded or rolled as the need arises.

Recently, to manufacture a flexible display device, research has beenconducted for replacing a glass substrate with a plastic substrate.However, replacing the glass substrate with the plastic substrate whenmanufacturing flexible display devices may be difficult.

SUMMARY

Embodiments of the present invention may provide planarized flexiblesubstrates.

Embodiments of the present invention may also provide methods ofmanufacturing the planarized flexible substrates.

According to an exemplary embodiment of the present invention, aflexible substrate includes a flexible mother substrate and aplanarization layer on the flexible mother substrate. Here, the flexiblemother substrate includes a transparent textile and a resin layer. Thetransparent textile includes a plurality of first transparent fibers anda plurality of second transparent fibers crossing the plurality of firsttransparent fibers, and the resin layer coats the transparent textile tofill a space between the first and second transparent fibers. Theplanarization layer includes an organic material having a curablecontraction rate of no greater than about 20%.

The resin layer may include at least one of epoxy resin, phenol resin,phenol-epoxy resin, bis male imide-triazin resin, polycarbonate,polyethersulfone, and polyetherimide.

A flatness of the planarization layer may be equal to or less than 100nm.

According to an exemplary embodiment of the present invention, a methodof manufacturing a flexible substrate may include: mounting a substrateon a first supporting substrate, forming an organic material layer onthe substrate; planarizing the organic material layer by pressuring theorganic material layer with a second supporting substrate opposite tothe first supporting substrate and curing the organic material layer.

The organic material layer may include an organic material having acurable contraction rate of no greater than about 20%.

The organic material may include at least one of 2(2-ethoxyethoxy) ethylacrylater, and polyethylene glycol diacrylate.

According to an exemplary embodiment of the present invention, a methodof manufacturing a flexible substrate may include: mounting a substrateon a supporting substrate, forming an organic material layer on thesubstrate, planarizing the organic material layer by pressuring theorganic material layer with a mold disposed opposite to the supportingsubstrate and curing the organic material layer. The organic materiallayer may include an organic material having a curable contraction rateof no greater than about 20%.

The mold may include a flat portion having a flat surface, and asidewall portion surrounding the flat portion. A thickness of theorganic material layer may be controlled by a height of the sidewallportion.

According to embodiments of the present invention, a method formanufacturing a flexible substrate is provided. The method includesforming a transparent textile including a plurality of first transparentfibers and a plurality of second transparent fibers intersecting withthe plurality of first transparent fibers, soaking the transparenttextile with a polymer resin in a liquid state in a container, removingthe transparent textile from the container and coating the transparenttextile with a resin layer such that the resin layer fills a spacebetween the first and second transparent fibers to thereby form aflexible mother substrate. The method further includes disposing theflexible mother substrate on a first supporting substrate having asubstantially flat surface, coating an organic material on the flexiblemother substrate, curing the organic material to form an organicmaterial layer on the flexible mother substrate, performing a soft bakeprocess on the organic material layer to remove a solvent in the organicmaterial layer.

In addition, the method further includes forming a desorption layer on asecond supporting substrate, bonding the first supporting substrate andthe second supporting substrate to each other such that the organicmaterial layer and the desorption layer face each other and a surface ofthe organic material layer contacting the desorption layer is planarizedby the bonding process, curing the organic material layer by a hard bakeprocess to form a planarization layer between the desorption layer andthe flexible mother substrate and removing the desorption layer from thesecond supporting substrate to thereby separate the second supportingsubstrate from the first supporting substrate and form a flexiblesubstrate which includes the flexible mother substrate and theplanarization layer which are sequentially stacked on the firstsupporting substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will become more apparentin view of the attached drawings and accompanying detailed description.

FIG. 1 is a schematic cross-sectional view illustrating a flexiblemother substrate according to an exemplary embodiment of the presentinvention;

FIGS. 2A through 2C are schematic views illustrating a method ofmanufacturing a flexible mother substrate according to an exemplaryembodiment of the present invention;

FIG. 3 is enlarged cross-sectional view of the flexible mother substratemanufactured by the method of FIGS. 2A through 2C;

FIGS. 4A through 4F are schematic cross-sectional views illustrating amethod of manufacturing a flexible substrate according to an exemplaryembodiment of the present invention;

FIG. 5A is an enlarged view of a portion ‘A1’ of FIG. 4B;

FIG. 5B is an enlarged view of a portion ‘A2’ of FIG. 4E;

FIGS. 6A through 6C are schematic cross-sectional views illustrating amethod of manufacturing a flexible substrate according to an exemplaryembodiment of the present invention;

FIGS. 7A through 7C are schematic cross-sectional views illustrating amethod of manufacturing a flexible substrate according to an exemplaryembodiment of the present invention;

FIG. 8 is an enlarged view of a portion ‘B1’ of FIG. 7B;

FIG. 9 is a schematic cross-sectional view illustrating a liquid crystaldisplay device including a flexible substrate according to an exemplaryembodiment of the present invention;

FIG. 10 is a schematic cross-sectional view illustrating an organicelectroluminescence display device including a flexible substrateaccording to an exemplary embodiment of the present invention; and

FIG. 11 is a schematic cross-sectional view illustrating anelectrowetting display device including a flexible substrate accordingto an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, a flexible mother substrate used in a method ofmanufacturing a flexible substrate according to an exemplary embodimentof the present invention will be explained with reference to FIGS. 1,2A, 2B, 2C, and 3. FIG. 1 is a schematic cross-sectional viewillustrating a flexible mother substrate, and FIGS. 2A through 2C areschematic views illustrating a method of manufacturing a flexible mothersubstrate in accordance with an exemplary embodiment of the presentinvention. FIG. 3 is enlarged cross-sectional view of the flexiblemother substrate manufactured by the method of FIGS. 2A through 2C.

Referring to FIG. 1, a flexible mother substrate 120 may be, forexample, a transparent substrate and may be flexible. For example, theflexible mother substrate 120 may be a film folded or rolled by anexternal force.

The flexible mother substrate 120 may include, for example, atransparent fiber therein. The transparent fiber may be, for example, aglass fiber. The transparent fiber may be woven to form a transparenttextile. For example, the transparent textile may be formed by weaving ayarn. The yarn may be made by twisting glass filaments into a strand.The weaving method may be one of, for example, a plain weave, a twillweave, a satin weave, a line weave, and imitation leno weave. However,exemplary embodiments of the present invention are not limited thereto.The flexible mother substrate 120 may be manufactured by, for example,soaking a glass fiber, a yarn using the glass fiber, or textile in atransparent resin. The flexible mother substrate 120 may be, forexample, a thin layer, a textile formed by weaving a fiber, or astructure stacking textiles or thin layers.

The flexible mother substrate 120 may be formed using, for example, anorganic resin. The organic resin may be a thermosetting resin such as,for example, epoxy resin, phenol resin, phenol-epoxy resin, and/or bismale imide-triazin resin, or a thermoplastic resin such aspolycarbonate, polyethersulfone and/or polyetherimide.

The flexible mother substrate 120 including the transparent textileformed using the transparent fiber will be described, hereinafter.

Referring to FIGS. 1 and 2A, the flexible mother substrate 120 mayprovide a base structure for forming a flexible substrate. The flexiblesubstrate may be modified by an external force. However, the flexiblesubstrate should support its structure against a predetermined externalforce.

The flexible mother substrate 120 may include, for example, atransparent textile 200 formed by weaving transparent fibers for havingan optical characteristic and a mechanical characteristic of theflexible substrate. Here, the mechanical characteristic means thermaldimension stability. As a material such as plastic has a largecoefficient of thermal expansion (CTE), the stability of a flexiblesubstrate formed by the material may decrease. However, because theflexible mother substrate 120 is formed using the transparent fiberssuch as, for example, the glass fibers, the CTE of the flexiblesubstrate may be reduced. In other words, because the CTE of the glassfibers is relatively smaller, the CTE of the flexible substrate can bereduced as the density of the glass fibers becomes higher. Thus, thestability of the flexible substrate can be increased. Here, the glassfibers may be woven in textile form, thereby controlling the CTEs of theflexible substrate in four directions to be substantially equal to eachother. The flexible mother substrate 120 is referred to as a fiberreinforced plastic.

A method of manufacturing the flexible mother substrate 120 inaccordance with an exemplary embodiment will be described, hereinafter.

Referring to FIG. 2A again, first transparent fibers 211 extending in atransverse direction relative to second transparent fibers 212 extendingin a longitudinal direction may be woven together to form a transparenttextile 200. The first and second transparent fibers 211 and 212 may be,for example, glass fibers. The transparent textile 200 may be formed of,for example, a transparent material to have an optical characteristictransmitting light. Intervals of the first transparent fibers 211 andthe second transparent fibers 212 may be controlled for the opticalcharacteristic and the mechanical characteristic of the transparenttextile 200.

Referring to FIG. 2B, the transparent textile 200 may be soaked in aliquid resin LR. The liquid resin LR may be, for example, a polymerresin and may be kept within a container BK in liquid state. After thetransparent textile 200 is completely soaked in the container BK, thetransparent textile 200 may be pulled from the container BK to form theflexible mother substrate 120.

Referring to FIGS. 2C and 3, the transparent textile 200 may be coatedwith, for example, a resin layer 220. The resin layer 220 may be curedto form the flexible mother substrate 120. At this time, the resin layer220 may be formed of, for example, a transparent resin transmittinglight. Here, the resin layer 220 may be formed using, for example, anorganic resin. The organic resin may be, for example, a thermosettingresin such as epoxy resin, phenol resin, phenol-epoxy resin, and/or bismale imide-triazin resin, or a thermoplastic resin such aspolycarbonate, polyethersulfone and/or polyetherimide.

Additionally, as the transparent textile 200 is fully coated with theresin layer 220, the resin layer 220 may exist between the first andsecond transparent fibers 211 and 212. In other words, the resin layer220 fills a space between the first and second transparent fibers 211and 212 constituting the transparent textile 200, such that the flexiblemother substrate 120 may get a desired mechanical characteristic.

A surface of the flexible mother substrate 120 may have significantroughness. For example, the surface of the flexible mother substrate 120may have a profile formed by the first and second transparent fibers 211and 212. In the flexible mother substrate 120, a portion in which thefirst and second transparent fibers 211 and 212 are disposed may be, forexample, convex relative to a portion of the flexible mother substrate120 in which the first and second transparent fibers 211 and 212 are notdisposed. That is, the flexible mother substrate 120 may have a wavysurface due to the first and second transparent fibers 211 and 212. Eventhough the space between the first and second transparent fibers 211 and212 is filled with the resin layer 220, the space may be relativelyconcave.

A method of manufacturing a flexible substrate according to an exemplaryembodiment of the present invention will be described with reference toFIGS. 4A through 4F. FIGS. 4A through 4F are schematic cross-sectionalviews illustrating a method of manufacturing a flexible substrateaccording to an exemplary embodiment of the present invention.

Referring to FIG. 4A, the flexible mother substrate 120 described abovemay be disposed on a first supporting substrate 100.

The first supporting substrate 100 may be formed of, for example, atransparent material. For example, the first supporting substrate 100may be a glass substrate. The glass substrate used for the firstsupporting substrate 100 may be, for example, a non-alkali glasssubstrate. Examples of the non-alkali glass material which may be usedin accordance with the present exemplary embodiment includes but is notlimited to aluminosilicate glass, aluminoborosilicate glass, bariumborosilicate glass, or the like. Moreover, the first supportingsubstrate 100 can instead be formed of, for example, quartz or sapphire.

Alternatively, the first supporting substrate 100 may be anon-transparent substrate. For example, the non-transparent substratemay be formed of plastic or metallic foils such as stainless steelfoils. The first supporting substrate 100 may have, for example, a flatsurface. The first supporting substrate 100 may support the flexiblemother substrate 120, so that the flexible mother substrate 120 maymaintain the flatness thereof. Even though not shown, a sacrificiallayer may be interposed between the first supporting substrate 100 andthe flexible mother substrate 120. Due to the sacrificial layer, theflexible mother substrate 120 may be readily separated from the firstsupporting substrate 100 in a subsequent process.

Referring to FIG. 4B, an organic material may be coated on the flexiblemother substrate 120 to form an organic material layer 130.

After the organic material is cured, the organic material may betransparent or non-transparent. Transparency of the organic material maybe selected depending on kinds of devices using the organic material andthe flexible mother substrate 120. The organic material may be cured bylight. For example, the organic material may be a photocurable resinsuch as HDDA(1,6-hexanediol-diacrylate), novolak resin), andHEBDM(bis(hydroxyethyl)bisphenol-A dimethacrylate). For example, theorganic material may be a material having a photo curable contractionrate of about 20% or less. The organic material may include monomers.The monomers of the organic material may be polymerized, so that theorganic material may be cured. At this time, weak bonds having long bondlengths may be transformed into strong bonds having short bond lengths.Thus, a cured layer is contracted. The curable contraction rate of theorganic material may be determined depending on a functional group and amonomer weight of the organic material. For example, the organicmaterial may be at least one of 2(2-ethoxyethoxy) ethyl acrylate, andpolyethylene glycol diacrylate.

Alternatively, the organic material may be cured by, for example, heat.For example, the organic material may include phenol resin, epoxy resin,silicon resin, acetate, and/or polyimide. For example, the organicmaterial may be a material having a thermal curable contraction rate ofabout 20% or less.

Accordingly, the organic material may be photocurable or thermosetting.

The organic material may be provided in, for example, a liquid state.The organic material may be diluted in a solvent to be provided. Theorganic material layer 130 may be formed by a method such as, forexample, a spin coating method, a slit coating method, a spray coatingmethod, and/or a ink jet coating method. The organic material layer 130may have a thickness sufficient to fill a concave region of the flexiblemother substrate 120. In an embodiment, as illustrated in FIG. 5A, theorganic material layer 130 may be coated, for example, along the surfaceprofile of the flexible mother substrate 120 to be non-flat.

The viscosity and the coating amount of the organic material mayinfluence the thickness of the organic material layer 130. In otherwords, the surface of the flexible mother substrate 120 may be moresmoothly planarized as the viscosity of the organic material becomesgreater, and the organic material layer 130 may be formed thicker due tothe viscosity. However, when the organic material layer 130 is thicker,the flexible mother substrate 120 may be bent by a stress of the organicmaterial layer 130. Thus, the thickness of the organic material layer130 may be controlled to reflect that phenomenon.

Referring to FIG. 4C, a soft bake process may be performed on theorganic material layer 130. The solvent in the organic material layer130 may be removed by the soft bake process.

Referring to FIG. 4D, a second supporting substrate 140 provided with adesorption layer 150 may be prepared. The desorption layer 150 may beformed on a surface of the second supporting substrate 140. The secondsupporting substrate 140 having a flat surface may be formed of amaterial transmitting light such as, for example, ultra violet (UV)light. Additionally, the second supporting substrate may be formed of amaterial transmitting heat. For example, the second supporting substrate140 may be a glass substrate. The glass substrate used for secondsupporting substrate 140 may be, for example, a non-alkali glasssubstrate. Examples of the non-alkali glass material which may be usedin accordance with the present exemplary embodiment includes but is notlimited to aluminosilicate glass, aluminoborosilicate glass, bariumborosilicate glass, or the like. Also, the second supporting substrate140 can instead be formed of, for example, a quartz substrate or asapphire substrate.

The desorption layer 150 may be formed of an inorganic material and/oran organic material. The desorption layer 150 may be formed of amaterial which is removable by a laser. At this time, the desorptionlayer 150 may be formed of a material removable by, for example, a powerless than an ablation power for removing the organic material layer 130.In other words, when the desorption layer 150 is removed by a laserbeam, the organic material layer 130 may not be removed. It is notedthat alternatively, the second supporting substrate 140 may instead beprepared before or simultaneously with the preparation of the firstsupporting substrate 100.

Referring to FIGS. 4C through 4E, a bonding process may be performed tobond the first supporting substrate 100 to the second supportingsubstrate 140 in the state that the organic material layer 130 and thedesorption layer 150 face each other. The bonding process may beperformed in a vacuum, and the first supporting substrate 100 and thesecond supporting substrate 140 may be pressed together.

The bonding process may be performed by a means such as, for example, aroller and/or an air cushion. Thus, air bubbles, which may exist betweenthe first and second supporting substrates 100 and 140, may be removed.Additionally, the first and the second supporting substrates 100 and 140are pressed together, so that the organic material layer 130 between thefirst and second supporting substrates 100 and 140 may be planarized. Inother words, the organic material layer 130 may be fluid between thefirst and second supporting substrates 100 and 140, so that a surface ofthe organic material layer 130 contacting the desorption layer 150 maybe planarized. Thus, as illustrated in 5B, even though the organicmaterial layer 130 is non-uniformly coated by the viscosity of theorganic material constituting the organic material layer 130, thesurface of the organic material layer 130 contacting the desorptionlayer 150 may be planarized by the bonding process. Here, the flatnessof the organic material layer 130 may be, for example, equal to or lessthan about 100 nm.

Subsequently, the organic material layer 130 may be cured by a hard bakeprocess to form a planarization layer 135. The planarization layer 135may have rigidity autonomously by the hard bake process. In anembodiment, to increase the flatness of the organic material layer 130,the first and second supporting substrates 100 and 140 may be pressedtogether during the hard bake process.

As described above, the soft bake process and the hard bake process maybe performed. However, a photocurable process besides the bake processesmay be selectively or abreast performed. The organic material may beselected depending on a curable process.

Referring to FIG. 4F, a removing process may be performed to remove thedesorption layer 150. The removing process may be performed using, forexample, a laser. The desorption layer 150 may be selectively removed bythe removing process to separate the second supporting substrate 140from the first supporting substrate 100. As a result, a flexiblesubstrate 180 may be formed. The flexible substrate 180 includes theflexible mother substrate 120 and the planarization layer 135 which aresequentially stacked on the first supporting substrate 100.

At least one surface of the flexible substrate 180 may include theplanarization layer 135. Processes may be performed on the planarizationlayer 135 to form devices such as, for example, a thin film transistorand/or a pixel electrode. In an embodiment, the processes described withreference to FIGS. 4A through 4F may be performed on another surface ofthe flexible substrate 180.

A method of manufacturing a flexible substrate according to an exemplaryembodiment of the present invention will be described with reference toFIGS. 6A through 6C. FIGS. 6A through 6C are schematic cross-sectionalviews illustrating a method of manufacturing a flexible substrateaccording to an exemplary embodiment of the present invention. The samedescriptions as described above will be omitted or mentioned briefly.

Referring to FIG. 6A, a barrier layer 160 may be formed on the productof FIG. 4D. Thus, the second supporting substrate 140 including thedesorption layer 150 and the barrier layer 160 sequentially stacked on asurface thereof may be prepared. The second supporting substrate 140 mayhave, for example, a flat surface and be formed of a materialtransmitting light such as ultra violet (UV) light. Additionally, thesecond supporting substrate 140 may be formed of a material transmittingheat. For example, the second supporting substrate 140 may be a glasssubstrate. The glass substrate used for the second supporting substrate140 may be, for example, a non-alkali glass substrate. Examples of thenon-alkali glass material which may be used in accordance with thepresent exemplary embodiment includes but is not limited toaluminosilicate glass, aluminoborosilicate glass, barium borosilicateglass, or the like. Further, the second supporting substrate 140 canalso be formed of, for example, a quartz substrate or a sapphiresubstrate.

The desorption layer 150 may be formed of an inorganic material and/oran organic material. The desorption layer 150 may be formed of amaterial which is removable by a laser. At this time, the desorptionlayer 150 may be formed of a material which is removable by, forexample, a power less than an ablation power for removing the barrierlayer 160.

The barrier layer 160 may be formed of a material having high lighttransmittance and low vapor permeability. For example, the barrier layer160 may be formed of an inorganic material such as silicon nitride.Alternatively, the barrier layer 160 may also be formed of otherinorganic materials such as, for example, silicon oxide, siliconoxynitride, silicon carbide, aluminum oxide, hafnium oxide, or tantalumoxide.

The processes described with reference to FIGS. 4A through 4C may beperformed again, so that the first supporting substrate 100 includingthe flexible mother substrate 120 and the organic material layer 130sequentially stacked on a surface thereof may be prepared. The firstsupporting substrate 100 and the second supporting substrate 140 may beprepared simultaneously or sequentially. A manufacturing order of thefirst and second supporting substrates 100 and 140 may be changed.

Referring to FIGS. 6A and 6B, a bonding process may be performed to bondthe first supporting substrate 100 to the second supporting substrate140, so that the organic material layer 130 and the barrier layer 160may face each other. The bonding process may be performed in a vacuum,and the first supporting substrate 100 and the second supportingsubstrate 140 may be pressed together.

The bonding process may be performed by using, for example, a rollerand/or an air cushion. Thus, air bubbles, which may exist between thefirst and second supporting substrates 100 and 140, may be removed.Additionally, the first and the second supporting substrates 100 and 140are pressed together, so that the organic material layer 130 between thefirst and second supporting substrates 100 and 140 may be planarized. Inother words, the organic material layer 130 may be fluid between thefirst and second supporting substrates 100 and 140, so that a surface ofthe organic material layer 130 contacting the barrier layer 160 may beplanarized. Thus, even though the organic material layer 130 isnon-uniformly coated by the viscosity of the organic materialconstituting the organic material layer 130, the organic material layer130 may be planarized by the bonding process.

Subsequently, the organic material layer 130 may be cured by, forexample, a hard bake process to form a planarization layer 135. Theplanarization layer 135 may have rigidity autonomously by the hard bakeprocess.

As described above, the soft bake process and the hard bake process maybe performed. However, a photocurable process besides the bake processesmay be selectively or abreast performed. The organic material may beselected depending on a curable process.

Referring to FIG. 6C, a removing process may be performed to remove thedesorption layer 150. The removing process may be performed using, forexample, a laser. The desorption layer 150 may be selectively removed bythe removing process to separate the second supporting substrate 140from the first supporting substrate 100. As a result, a flexiblesubstrate 185 may be formed which includes the flexible mother substrate120, the planarization layer 135, and the barrier layer 160 which aresequentially stacked on the first supporting substrate 100.

Hereinafter, a method of manufacturing a flexible substrate according toan exemplary embodiment of the present invention will be described withreference to FIGS. 7A through 7C. FIGS. 7A through 7C are schematiccross-sectional views illustrating a method of manufacturing a flexiblesubstrate according to an exemplary embodiment of the present invention;

Referring to FIG. 7A, the processes described with reference to FIGS. 4Aand 4B may be performed to form the flexible mother substrate 120 andthe organic material layer 130 sequentially stacked on the firstsupporting substrate 100. The organic material layer 130 may bepre-baked as the need arises.

A mold 50 for planarizing the organic material layer 130 may beprepared. The mold 50 may include, for example, a flat portion 51 havinga flat surface, and a sidewall portion 52 surrounding the flat portion51. In other words, the mold 50 may have, for example, a box shape ofwhich a side is opened by the flat portion 51 and the sidewall portion52. At this time, the flat portion 51 may be formed of a materialtransmitting light such as, for example, UV light irradiated insubsequent process, and/or heat. For example, the flat portion 51 may beformed of a transparent material such as, for example, a glasssubstrate. Alternatively, the flat portion 51 may be formed of othertransparent materials including, for example, a sapphire substrate or aquartz substrate.

The sidewall portion 52 surrounding the flat portion 51 may control athickness of the organic material layer 130. That is, the thickness ofthe organic material layer 130 may be controlled according to, forexample, a coating amount and a height of the sidewall portion 52.

Referring to FIG. 7B, the organic material layer 130 may be pressured bythe mold 50 to be planarized. The organic material layer 130 may not beuniformly coated on the flexible mother substrate 120 by the viscosityof the organic material. However, if an organic material having lowviscosity is used, the flexible mother substrate 120 should be coatedseveral times. If the coating process is repeatedly performed severaltimes, the flexible mother substrate 120 may be bent by an autonomousstress of a coating layer. Thus, the organic material having a suitableviscosity may be coated on the flexible mother substrate 120 and thenthe organic material may be pressured using the mold 50, therebyplanarizing the organic material layer 130.

The organic material layer 130 may be cured by a curable process to forma planarization layer 138. As the organic material layer 130 may beformed by coating the organic material in a liquid state not to have aself-rigidity, the curable process is performed. As illustrated in FIG.8, a surface of the planarization layer 138 may become flat along asurface profile of the flat portion 51.

The curable process may be, for example, a UV treatment process or athermal treatment process. At this time, the curable process may be, forexample, one of a UV irradiation or a thermal treatment. When theorganic material layer 130 is formed of a photocurable resin,irradiation of a visible light or the UV light may be performed.Alternatively, when the organic material layer 130 is formed of athermosetting resin, the heat treatment may be performed. Additionally,the heat treatment and the UV irradiation may be performed abreastaccording to a kind of the organic material constituting the organicmaterial layer 130.

Referring to FIG. 7C, the mold 50 may be separated from the firstsupporting substrate 100. Thus, a flexible substrate 188 may include theflexible mother substrate 120 and the planarization layer 138sequentially stacked on the first supporting substrate 100.

In the above embodiment, the planarization layer 138 is formed on onesurface of the flexible substrate 188. However, the planarization layer138 may also be formed on another surface of the flexible substrate 188.Thus, the processes described with reference to FIGS. 7A through 7C mayalso be performed on another surface of the flexible substrate 188 asthe need arises.

Hereinafter, a display device including a flexible substrate accordingto an exemplary embodiment of the present invention will be describedwith reference to FIG. 9. FIG. 9 is a schematic cross-sectional viewillustrating a liquid crystal display device including a flexiblesubstrate according to an exemplary embodiment of the present invention.

Referring to FIG. 9, a liquid crystal display device may include, forexample, an array substrate 300, an opposite substrate 390 facing thearray substrate 300, a liquid crystal layer 350 interposed between thearray substrate 300 and the opposite substrate 390, and an array layer330 formed on the array substrate 300. The array substrate 300 and/orthe opposite substrate 390 may be, for example, one of the flexiblesubstrates 180, 185, or 188 described with reference to FIG. 4F, 6C, or7C. Here, surfaces of the array substrate 300 and the opposite substrate390, on which the planarization layers 135, or 138 are formed, may beopposite to each other.

Even though not shown, the array layer 330 may include gate lines (nowshown) and data lines (not shown) which extend to cross each other onthe array substrate 300. The gate lines and the data lines may be formedby, for example, performing a deposition process of a conductivematerial on the flexible substrate of FIG. 4F, 6C, or 7C and apatterning process of the conductive material. Pixel regions (not shown)may be defined by the gate lines and the data lines, and pixelscorresponding to the pixel regions may be provided.

Each of the pixels may include a thin film transistor (TFT, not shown)and a pixel electrode (not shown). Here, a gate electrode of the TFT maybe connected to a corresponding gate line, a source electrode of the TFTmay be connected to a corresponding data line, and a drain electrode ofthe TFT may be connected to the pixel electrode.

The opposite substrate 390 may include, for example, RGB color pixelsrespectively corresponding to the pixels, and a common electrode formedon the RGB color pixel and facing the pixel electrode.

The liquid crystal layer 350 may be arranged in a predetermineddirection by an electric field generated between the pixel electrode andthe common electrode, so that a transmittance of a light provided froman external light source may be controlled.

A display device including a flexible substrate according to anexemplary embodiment of the present invention will be described withreference to FIG. 10. FIG. 10 is a schematic cross-sectional viewillustrating an organic electroluminescence display device including aflexible substrate according to an exemplary embodiment of the presentinvention.

Referring to FIG. 10, an organic electroluminescence display device mayinclude, for example, a flexible substrate 400, a pixel electrode 460,an organic layer 470, and an upper electrode 480. The pixel electrode460, the organic layer 470, and the upper electrode 480 may besequentially stacked on the flexible substrate 400. The flexiblesubstrate 400 may be, for example, one of the flexible substrates 180,185, 188 described with reference to FIG. 4F, 6C, or 7C. Here, the pixelelectrode 460, the organic layer 470, and the upper electrode 480 may besequentially stacked on a surface of the flexible substrate 400 on whichthe planarization layer 135 or 138 is formed.

The pixel electrode 460 and the upper electrode 480 may be a transparentor not-transparent conductive layer. The pixel electrode 460 may provideholes to the organic layer 470, and the upper electrode 480 may provideelectrons to the organic layer 470. Alternatively, the pixel electrode460 may provide electrons to the organic layer 470, and the upperelectrode 480 may provide holes to the organic layer 470. The organiclayer 470 may be single-layered or multi-layered. The holes and theelectrons may be combined with each other to emit light toward theoutside.

In addition, a thin film transistor may further be provided on theflexible substrate 400. Additionally, an insulating layer covering thethin film transistor may further formed between the flexible substrate400 and the pixel electrode 460. The thin film transistor may beprovided in plural. For example, the thin film transistors may include aswitching transistor and a driving transistor. The pixels may beselected individually by the switching transistor, and the pixel may bedriven by the driving transistor.

Additionally, a packaging structure may further be provided. Thepackaging structure may be opposite to the flexible substrate 400, andprotect the pixel electrode 460, the organic layer 470, and the upperelectrode 480.

A display device including a flexible substrate according to anexemplary embodiment of the present invention will be described withreference to FIG. 11. FIG. 11 is a schematic cross-sectional viewillustrating an electrowetting display device including a flexiblesubstrate according to an exemplary embodiment of the present invention.

Referring to FIG. 11, an electrowetting display device may include, forexample, a first substrate 500 and a second substrate 590 opposite toeach other, and a fluid layer 560 between the first and secondsubstrates 500 and 590. At least one of the first substrate 500 and thesecond substrate 590 may be one of the flexible substrates 180, 185, or188 described with reference to FIG. 4F, 6C, or 7C. Surfaces of thefirst and second substrates 500 and 590, on which the planarizationlayers 135 or 138 are formed, may be opposite to each other.

A pixel wall 520 may be disposed on the first substrate 500. A pixelregion PA may be defined by the pixel wall 520. The pixel wall 520 mayinclude, for example, an organic material. The organic material of thepixel wall 520 may be, for example, photocurable material. The pixelwall 520 may include a top surface facing the second substrate 590. Thetop surface may be, for example, a hydrophilic treated surface.

A pixel electrode 530 may be disposed on the pixel region PA. The pixelelectrode 530 may be a transparent conductive layer or a reflectionconductive layer. Alternatively, the pixel electrode 530 may include allof the transparent conductive layer and the reflection conductive layer.

A hydrophobic insulating layer 555 may be disposed on the pixelelectrode 530. For example, the hydrophobic insulating layer 555 mayinclude a hydrophobic material such as, for example, apolytetrafluoroethylene resin (PTFE),polytetrafluoroethylene-perfluoroalkoxyethylen copolymer resin (PFA) orpoly tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP) eachsold under the brand name TEFLON® which is a registered trademark of theE.I. DuPont de Nemours and Company Corporation, 101 West 10th St.,Wilmington, Del. 19898. Moreover, the hydrophobic insulating layer 555may also include other hydrophobic materials such as, for example,polyperflouro-butenylvinylether sold under the brand name CYTOP®, whichis a registered trademark of Asahi Glass co., Ltd.

A common electrode 592 may be disposed on the second substrate 590. Thecommon electrode 592 may be disposed on a surface of the secondsubstrate 590 opposite to the first substrate 500. The common electrode592 may be, for example, a transparent electrode.

The fluid layer 560 may include, for example, a polarity fluid 565 and anon-polarity fluid 561. The non-polarity fluid 561 and the polarityfluid 565 may not be mixed to form a boundary. The non-polarity fluid561 and the polarity fluid 565 may be located between the firstsubstrate 500 and the second substrate 590. For example, thenon-polarity fluid 561 may be an oil material, and the polarity fluid565 may be a electrolyte solution such as water. The polarity fluid 565may be shared by the pixel regions PA neighboring with each other. Thenon-polarity fluid 561 may be disposed and confined in each of the pixelregions PA. That is, the non-polarity fluids 561 in the pixel regions PAmay be spaced apart from each other. The non-polarity fluid 561 may be,for example, non-transparent. Or the non-polarity fluid 561 may have acolor autonomously. Alternatively, the non-polarity fluid 561 may have,for example, a color by a dye or a pigment. On the other hand, thepolarity fluid 565 may be, for example, transparent.

Even though not shown, thin film transistors (not shown) and aninterlayer insulating layer (not shown) covering the thin filmtransistors may further be disposed on the first substrate 500. The thinfilm transistors may be connected in series to constitute a switchingarray selecting each of unit pixels. The interlayer insulating layer maytransmit light. The interlayer insulating layer may include, forexample, an organic material and/or an inorganic material, and theorganic material may be a photocurable material. The interlayerinsulating layer may be formed with, for example, a thickness for havinga planarized top surface so that a winding caused by the thin filmtransistor does not appear.

According to an exemplary embodiment of the present invention, anorganic material layer on a flexible mother substrate may be pressuredto be planarized using a substrate or a mold opposite to a supportingsubstrate. Thus, a stress may not be supplied to the flexible mothersubstrate, such that a flexible substrate may be readily manufactured.If a viscosity of an organic material is lower, the organic material maybe coated on the flexible mother substrate several times. Thus, theprocess time and the cost may increase and a stress supplied to theflexible mother substrate may increase. If a viscosity of an organicmaterial is higher, the organic material may be non-uniformly formed onthe flexible mother substrate. According to an exemplary embodiment ofthe present invention, a planarization layer may be formed by arelatively simple process to reduce the process costs. Additionally, theabove-mentioned difficulties may be avoided and/or decreased.

Having described exemplary embodiments of the inventive concept, it isfurther noted that it is readily apparent to those of reasonable skillin the art that various modifications may be made without departing fromthe spirit and scope of the invention which is defined by the metes andbounds of the appended claims.

1. A flexible substrate comprising: a flexible mother substrateincluding a transparent textile and a resin layer, the transparenttextile including a plurality of first transparent fibers and aplurality of second transparent fibers crossing the plurality of firsttransparent fibers, wherein the resin layer coating the transparenttextile to fill a space between the first and second transparent fibers;and a planarization layer disposed on the flexible mother substrate andincluding an organic material having a curable contraction rate of nogreater than about 20%.
 2. The flexible substrate of claim 1, whereinthe resin layer includes at least one of a epoxy resin, a phenol resin,a phenol-epoxy resin, a bis male imide-triazin resin, a polycarbonate, apolyethersulfone, and a polyetherimide.
 3. The flexible substrate ofclaim 1, wherein a flatness of the planarization layer is no greaterthan about 100 nm.
 4. The flexible substrate of claim 1, wherein theorganic material includes at least one of 2(2-ethoxyethoxy) ethylacrylater, and polyethylene glycol diacrylate.
 5. A method ofmanufacturing a flexible substrate, comprising: mounting a substrate ona first supporting substrate; forming an organic material layer on thesubstrate; planarizing the organic material layer by pressuring theorganic material layer with a second supporting substrate opposite tothe first supporting substrate; and curing the organic material layer.6. The method of claim 5, wherein the curing of the organic materiallayer comprises providing at least one of heat and light to the organicmaterial layer.
 7. The method of claim 6, further comprising; providingthe heat and/or the light to the organic material layer before theplanarizing of the organic material layer.
 8. The method of claim 6,further comprising: forming a desorption layer on a surface of thesecond supporting substrate before the planarizing of the organicmaterial layer, wherein the surface of the second supporting substratefaces the organic material layer.
 9. The method of claim 8, furthercomprising: forming a barrier layer protecting the organic materiallayer on the desorption layer.
 10. The method of claim 8, furthercomprising: removing the desorption layer to separate the secondsupporting substrate from the first supporting substrate.
 11. The methodof claim 6, wherein the organic material layer includes an organicmaterial having a curable contraction rate of no greater than about 20%.12. The method of claim 11, wherein the organic material includes atleast one of 2(2-ethoxyethoxy) ethyl acrylater, and polyethylene glycoldiacrylate.
 13. The method of claim 5, wherein the first supportingsubstrate is a glass substrate.
 14. The method of claim 5, wherein thesecond supporting substrate is a glass substrate.
 15. The method ofclaim 5, wherein the substrate is a fiber reinforced plastic.
 16. Amethod of manufacturing a flexible substrate, comprising: mounting asubstrate on a supporting substrate; forming an organic material layeron the substrate; planarizing the organic material layer by pressuringthe organic material layer with a mold disposed opposite to thesupporting substrate; and curing the organic material layer, wherein theorganic material layer includes an organic material having a curablecontraction rate of no greater than about 20%.
 17. The method of claim16, wherein the mold includes a flat portion having a flat surface, anda sidewall portion surrounding the flat portion; and wherein a thicknessof the organic material layer is controlled by a height of the sidewallportion.
 18. The method of claim 17, wherein the curing of the organicmaterial layer comprises providing at least one of heat and light to theorganic material layer.
 19. The method of claim 16, wherein the organicmaterial includes at least one of 2(2-ethoxyethoxy) ethyl acrylater, andpolyethylene glycol diacrylate.
 20. The method of claim 16, wherein thesubstrate is a fiber reinforced plastic.
 21. A method for manufacturinga flexible substrate, comprising: forming a transparent textileincluding a plurality of first transparent fibers and a plurality ofsecond transparent fibers intersecting with the plurality of firsttransparent fibers; soaking the transparent textile with a polymer resinin a liquid state in a container; removing the transparent textile fromthe container and coating the transparent textile with a resin layersuch that the resin layer fills a space between the first and secondtransparent fibers to thereby form a flexible mother substrate;disposing the flexible mother substrate on a first supporting substratehaving a substantially flat surface; coating an organic material on theflexible mother substrate; curing the organic material to form anorganic material layer on the flexible mother substrate; performing asoft bake process on the organic material layer to remove a solvent inthe organic material layer; forming a desorption layer on a secondsupporting substrate; bonding the first supporting substrate and thesecond supporting substrate to each other such that the organic materiallayer and the desorption layer face each other and a surface of theorganic material layer contacting the desorption layer is planarized bythe bonding process; curing the organic material layer by a hard bakeprocess to form a planarization layer between the desorption layer andthe flexible mother substrate; and removing the desorption layer fromthe second supporting substrate to thereby separate the secondsupporting substrate from the first supporting substrate and form aflexible substrate which includes the flexible mother substrate and theplanarization layer which are sequentially stacked on the firstsupporting substrate.
 22. The method of claim 21, wherein the first andsecond transparent fibers each include glass fibers and wherein theforming of the transparent textile includes weaving the glass fibers ofthe first and second transparent fibers together.
 23. The method ofclaim 21, wherein the bonding of the first and second supportingsubstrates to each other is performed in a vacuum and wherein thedesorption layer is removed using a laser.